The present invention relates to hearing aids having an implantable part, and particularly cochlear prosthetic devices with no percutaneous connections.
Radiolinked cochlear prosthetic devices which operate in conjunction with hearing aids and speech processors utilizing digital encoding and time division multiplexing have been reported. These systems can suffer from loss of transmitter/receiver synch due to a rf link drop out, insufficient audio amplitude resolution, and limited audio bandwidth. Transcutaneous speech signal transmission systems utilizing ultrasound and modulated infra red light have also been reported with attendant difficulties of the need for coupling gels, accurate and stable alignment of transducers, and impractically large power requirements.